Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Other Liabilities
Interest rate swap contracts, Current	$ 11,724	$ 16,533
Asset retirement obligations	10,829	9,821
Deferred revenue, Current	276	249
Other, Current	9,964	1,634
Total current portion of other long-term liabilities	32,793	28,237
Acquisition-related contingent consideration	43,175
Interest rate swap contracts, Noncurrent	12,510	14,456
Deferred revenue, Noncurrent	1,877	1,698
Other, Noncurrent	10,859	2,537
Total other long-term liabilities	$ 68,421	$ 18,691